INS and type 2 diabetes mellitus: In a 46-study meta-analysis (n = 913), vinegar acutely reduced postprandial glucose [standardized mean difference (SMD) −0.53 (95% CI −0.92, −0.14) in impaired glucose tolerance/T2D; −0.27 (−0.54, 0.00) in healthy adults], while acute acetate and acute/chronic propionate showed no significant effects on glucose or insulin [134].